Effect of abnormal grain growth on microstructure and mechanical properties of friction stir welded SPCC steel plates

Friction stir welding (FSW) is an alternative method to join aluminum (Al) alloys in a solid-state condition. However, the coarsening or dissolution of precipitation hardening phases in the welding zone causes strength reduction or softening behavior in the welded area of age-hardened Al alloys. Therefore, this research aimed to improve the mechanical properties of an FSW Al–Mg–Si alloy via post-weld heat treatment (PWHT) and the possibility of controlling the abnormal grain growth (AGG) using different welding parameters. FSW was performed with different rotational and travel speeds, and T6 heat treatment was carried out on the FSW samples as the PWHT. The results showed a decrease in the strength of the FSW samples compared with that of the base material (BM) due to the dissolution of precipitation hardening particles in the heat-affected zone. However, the emergence of AGG in the microstructure after the T6-PWHT was identified as the potential event in the microstructure of the PWHT samples. It is found that the AGG of the microstructure in similar joints of Al6061(T6) was governed by the welding parameters. The results proved that PWHT was able to increase the tensile properties of the welded samples to values comparable to that of Al6061(T6)-BM. The increased mechanical properties of the FSW joints were attributed to a proper PWHT that resulted in a homogeneous distribution of the precipitation hardening phases in the welding zones.

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Effect of MgO-Y2O3 Additions on Microstructure and Mechanical Properties of Al2O3-TiCN Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1058.176 ◽

2014 ◽

Vol 1058 ◽

pp. 176-179

Author(s):

Zhi Lin Zhang ◽

Wei Ming Guo ◽

Shang Hua Wu ◽

Yang You

Keyword(s):

Mechanical Properties ◽

Fracture Toughness ◽

Grain Growth ◽

Abnormal Grain Growth ◽

Microstructure And Mechanical Properties

The effect of MgO-Y2O3 additives on densification, microstructure and mechanical properties of hot-pressed Al2O3-TiCN composites was studied. The MgO-Y2O3 additions had little influence on densification of Al2O3-TiCN composites. The Al2O3-TiCN composites without additives had coarsening microstructure, whereas that containing 0.25wt%MgO-0.5wt%Y2O3 had a noticeable finer microstructure and good mechanical properties. The increase of fracture toughness were attributed to the addition of MgO and Y2O3 together with the TiCN particles to inhibit the abnormal grain growth of Al2O3.

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Effect of Rotation Speed on Microstructure and Mechanical Properties of Friction-Stir-Welded 2205 Duplex Stainless Steel

Advances in Materials Science and Engineering ◽

10.1155/2020/5176536 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Wenyang Wang ◽

Ye Hu ◽

Tong Wu ◽

Dan Zhao ◽

Hongwei Zhao

Keyword(s):

Mechanical Properties ◽

Heat Input ◽

Rotation Speed ◽

Steel Plates ◽

Welding Temperature ◽

Friction Stir ◽

Microstructure And Mechanical Properties ◽

Joint Width ◽

Thick Steel ◽

Lower Heat

In the present study, 1.86-mm-thick steel plates (UNS S32205) were friction-stir-welded at various rotation speeds of 300 to 600 rpm and a constant welding speed of 100 mm·min−1. The effect of rotation speed on the microstructure and mechanical properties of the welds was researched. The welding temperature was recorded during friction stir welding (FSW), and the microstructure and mechanical properties of the welds were assessed. The incomplete penetration defect was formed at 300 rpm due to the insufficient heat input, and macroscopic groove-like defect was formed at 600 rpm because of the serious sticking of tool. Defect-free welds were obtained at 350 to 500 rpm. The lower rotation speed corresponds to lower heat input during FSW, which resulted in finer recrystallized grains within the stirred zone and thermomechanically affected zone. The joint width was increased with the increasing rotation speed. Therefore, both the strength and hardness of the weld joints increased with the decreasing of rotation speed.

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